PARKINSON DISEASE (PD) IS A

Transcription

1 ORIGINAL CONTRIBUTION Dopamine Transporter Brain Imaging to Assess the Effects of vs on arkinson Disease rogression arkinson Study Group ARKINSON DISEASE (D) IS A slow but relentlessly progressive neurodegenerative disorder characterized clinically by bradykinesia, tremor, rigidity, and gait dysfunction. The clinical decline reflects ongoing nigrostriatal dopaminergic degeneration. 1-3 Dopaminergic replacement therapy with the precursor levodopa or agonists that stimulate the dopamine receptor is effective in ameliorating many signs and symptoms of early D. However, progressive neuronal degeneration ultimately results in severe motor, mental, and functional disability. Increasing evidence from laboratory and animal studies suggests that in addition to their symptomatic effects, levodopa and dopamine receptor agonists may either accelerate or slow the dopaminergic degeneration of D. Recent data regarding the effects of levodopa have been controversial with in vitro data supporting both a potential toxic and protective effect on dopaminergic neurons. 4,5 Studies have demonstrated that dopamine receptor agonists protect cultured dopaminergic neurons from potential levodopa toxicity and may exert direct antioxidant and receptor-mediated antiapoptotic effects. 6-8 The putative neurotoxic or neuroprotective actions of levodopa or dopamine receptor agonists have provided the rationale for assessing the progression of dopamine neuronal degeneration in patients with D after treatment with these drugs. Context and levodopa are effective medications to treat motor symptoms of early arkinson disease (D). In vitro and animal studies suggest that pramipexole may protect and that levodopa may either protect or damage dopamine neurons. Neuroimaging offers the potential of an objective biomarker of dopamine neuron degeneration in D patients. Objective To compare rates of dopamine neuron degeneration after initial treatment with pramipexole or levodopa in early D by means of dopamine transporter imaging using single-photon emission computed tomography (SECT) with 2 carboxymethoxy-3 (4-iodophenyl)tropane ( -CIT) labeled with iodine 123. Design Substudy of a parallel-group, double-blind randomized clinical trial. Setting and atients Eighty-two patients with early D who were recruited at 17 clinical sites in the United States and Canada and required dopaminergic therapy to treat emerging disability, enrolled between November 1996 and August Interventions atients were randomly assigned to receive pramipexole, 0.5 mg 3 times per day with levodopa placebo (n=42), or carbidopa/levodopa, 25/100 mg 3 times per day with pramipexole placebo (n=40). For patients with residual disability, the dosage was escalated during the first 10 weeks, and subsequently, open-label levodopa could be added. After 24 months of follow-up, the dosage of study drug could be further modified. Main Outcome Measures The primary outcome variable was the percentage change from baseline in striatal [ 123 I] -CIT uptake after 46 months. The percentage changes and absolute changes in striatal, putamen, and caudate [ 123 I] -CIT uptake after 22 and 34 months were also assessed. Clinical severity of D was assessed using the Unified arkinson Disease Rating Scale (UDRS) 12 hours off anti-d medications. Results Sequential SECT imaging showed a decline in mean (SD) [ 123 I] -CIT striatal uptake from baseline of 10.3% (9.8%) at 22 months, 15.3% (12.8%) at 34 months, and 20.7% (14.4%) at 46 months approximately 5.2% per year. The mean (SD) percentage loss in striatal [ 123 I] -CIT uptake from baseline was significantly reduced in the pramipexole group compared with the levodopa group: 7.1% (9.0%) vs 13.5% (9.6%) at 22 months (=.004); 10.9% (11.8%) vs 19.6% (12.4%) at 34 months (=.009); and 16.0% (13.3%) vs 25.5% (14.1%) at 46 months (=.01). The percentage loss from baseline in striatal [ 123 I] -CIT uptake was correlated with the change from baseline in UDRS at the 46-month evaluation (r= 0.40; =.001). Conclusions atients initially treated with pramipexole demonstrated a reduction in loss of striatal [ 123 I] -CIT uptake, a marker of dopamine neuron degeneration, compared with those initially treated with levodopa, during a 46-month period. These imaging data highlight the need to further compare imaging and clinical end points of D progression in long-term studies. JAMA. 2002;287: Members of the arkinson Study Group and Financial Disclosures are listed at the end of this article. Corresponding Author and Reprints: Kenneth Marek, MD, The Institute for Neurodegenerative Disorders, 60 Temple St, Suite 8B, New Haven, CT ( kmarek@indd.org) American Medical Association. All rights reserved. (Reprinted) JAMA, April 3, 2002 Vol 287, No

2 During the past decade, in vivo imaging of the nigrostriatal dopaminergic system has been developed as a research tool to monitor progressive dopaminergic neuron loss in D. Several reports have demonstrated that at the time of emergence of D symptoms there is a loss of approximately 40% to 60% of dopaminergic markers in the striatum In longitudinal studies of D progression, imaging ligands targeting both dopamine metabolism fluorine 18 fluorodopa ([ 18 F]DOA) and dopamine transporter density iodine 123 (2 -carboxymethoxy-3 [4-iodophenyl]tropane [ 123 I] -CIT) and fluorine 18 (2 -carboxymethoxy-3 tropane [ 18 F]CFT) using both positron emission tomography and single-photon emission computed tomography (SECT) have demonstrated an annualized rate of reduction in striatal [ 18 F]DOA, [ 18 F]CFT, or [ 123 I] -CIT uptake of approximately 6% to 13% in patients with D compared with 0% to 2.5% change in healthy controls These imaging studies are consistent with pathological studies showing that the rate of nigral degeneration in patients with D was 8- to 10-fold that of healthy, age-matched controls. 2,20 We have used in vivo imaging of the dopamine transporter with [ 123 I] - CIT and SECT to assess the progression of dopaminergic degeneration in a subset of patients with early D participating in a clinical trial that compared the option of initial treatment with pramipexole with the option of initial treatment with levodopa. The clinical study (called CALM-D) was a multicenter, parallel-group, double-blind, randomized clinical trial comparing the option of initial treatment with pramipexole or levodopa with regard to the development of dopaminergic motor complications and changes associated with function and quality of life. 21 After 2 years of prospective follow-up, initial treatment with pramipexole delayed the onset of dopaminergic motor complications compared with levodopa therapy but initial levodopa therapy was more effective than pramipexole in ameliorating signs and symptoms of D. 22 In this report, we present the 4-year follow-up of the subset of study patients who have undergone sequential [ 123 I] -CIT SECT imaging to compare the rate of loss of the dopamine transporter, a marker for dopamine nerve terminal loss, between the groups treated initially with pramipexole or levodopa. METHODS The methods and results of the CALM-D trial after 2 years of follow-up have been previously reported. 21,22 With patient informed consent, the trial was extended to a 4-year follow-up with maintenance of the parallel-group, double-blind, randomized design. The methods and outcomes of the imaging substudy, called CALM-D-CIT, are described herein. The CALM-D clinical outcomes at 4 years will be reported separately. A total of 82 of the 301 patients in the CALM-D trial, enrolled between November 1996 and August 1997, participated in the imaging substudy. Research participants in the imaging substudy were recruited at 17 clinical sites (14 in the United States and 3 in Canada) and traveled to the imaging center in New Haven, Conn, for up to 4 imaging assessments. The imaging study was approved by the institutional review board and radiation safety committee. All patients gave written informed consent. Study Design CALM-D. Complete eligibility requirements for the trial have been previously detailed. 21 Eligible patients were randomized with equal allocation to each of the 2 treatment groups (pramipexole group or carbidopa/levodopa group) using a computer-generated randomization plan. articipation in the imaging substudy was not considered in the randomization plan. All patients enrolled at sites that chose to participate in the imaging substudy were offered the option, but were not required to participate in the -CIT SECT substudy. Baseline imaging was completed prior to randomization. atients took study drugs orally 3 times daily, approximately 6 (SD, 2) hours apart, throughout the study. Initially patients entered a 10-week dosage escalation period to reach one of the predetermined dosage levels: 1.5 mg of pramipexole or 75 or 300 mg of carbidopa/levodopa (level 1 dosage); 3.0 mg of pramipexole or or 450 mg of carbidopa/levodopa (level 2 dosage); or 4.5 mg of pramipexole or 150 or 600 mg of carbidopa/levodopa (level 3 dosage). Study drug was then maintained at that level until 24 months after baseline, and subsequently the dosage level could be modified during an additional 22- to 36-month evaluation period. atients with emerging disability posing a threat to ambulation, activities of independent living, or gainful employment were prescribed openlabel carbidopa/levodopa as needed. CALM-D-CIT [ 123 I] -CIT and SECT Substudy. All patients in CALM-D-CIT were evaluated sequentially with imaging studies at baseline and 22, 34, and 46 months after baseline as indicated in FIGURE 1. Thirteen patients also underwent imaging studies at 10 weeks after baseline to assess short-term effects of study drugs on the imaging outcome. Imaging Data Acquisition and Image Analysis High specific-activity [ 123 I] -CIT was prepared from the corresponding trimethylstannyl precursor as previously described. 23 atients were injected with a 6-mCi (222-MBq) dosage of [ 123 I] -CIT after pretreatment with Lugol solution to prevent thyroid uptake of any free 123 I. One hundred twenty raw projection images were acquired in a matrix into a 20% energy window centered on 159 kev at a mean of 24 (SD, 2) hours following injection on a 3-headed detector SECT system (icker rism 3000X; Marconi Medical, Cleveland, Ohio) fitted with low-energy, high-resolution fan beam collimators. rojection data were filtered with a standardized 2-dimensional Butterworth filter and reconstructed using a 1654 JAMA, April 3, 2002 Vol 287, No. 13 (Reprinted) 2002 American Medical Association. All rights reserved.

3 ramp filter. Spatial resolution for this reconstruction method is a full width at half maximum of 12.2 mm measured with a 123 I line source in a 20-cm cylindric phantom filled with water. Attenuation correction ellipses were fit using a Chang zero order (homogeneous) correction applied to the reconstructed data. 24 Four contiguous transaxial slices with the highest uptakes in striatum were identified and digitally summed to yield a transaxial slice 14.2 mm thick. This plane of slice is a noted distance superior to and parallel with the canthomeatal line. Standard uniform, circular regions of interest for left and right caudate and putamen, and a larger region of interest for the background cortical region (occipital cortex) were drawn using previously described operationalized criteria. 15,25 All analyses were completed by a single technologist (M.E.) blinded to any patient information. While the study was ongoing, an improvement in the reconstruction algorithm was introduced by the camera manufacturer, which modified the equilibrium brain tissue distribution volume by improving the reconstruction for regions with low counts. reliminary findings from the baseline to 22- month scan were reported 22 using the old reconstruction algorithm. All raw projection data from the baseline and 22-month scan were subsequently reanalyzed with the improved algorithm and reported herein in conjunction with month 34 and 46 scan data. The decision to use the reanalyzed raw projection data in the statistical analysis of this study was made before data analysis and while investigators were blinded to treatment assignment. Clinical Assessment All study participants were evaluated after 12 hours without study drug and anti-d medications, the defined off state, with Unified arkinson Disease Rating Scale (UDRS) and Hoehn and Yahr scores determined at the imaging center before each imaging study The clinical investigator was blinded to treatment assignment. Figure 1. atient Flow Diagram Completed Imaging Studies 42 At Baseline 7 At 10 wk At 22 mo 35 At 34 mo 33 At 46 mo 7 Withdrew From CALM-D but Continued in CALM-D-CIT 1 At 34 mo (Lack of Efficacy) 6 At 46 mo 4 Lack of Efficacy 2 Other 9 Withdrew From CALM-D-CIT 3 At 22 mo 2 Died 1 Symptoms of D Worsened 3 At 34 mo 1 Other Illness 2 Desired to End Study articipation 3 At 46 mo 2 Died 1 Desired to End Study articipation 301 atients Enrolled in CALM-D Trial 82 Enrolled in CALM-D-CIT (Imaging Substudy) 82 Randomized Outcome Variables The prespecified primary outcome variable in this study was the percentage change from baseline to month 46 in the specific-nondisplaceable striatal [ 123 I] -CIT uptake ratio, a tissue equilibrium distribution volume sampled in regions of caudate and putamen that is linearly related to the density of dopamine transporter binding sites in brain. 29,30 Specific uptake was determined by subtracting occipital densities (nondisplaceable uptake) from total caudate and/or putamen count densities and dividing by the occipital background region. Striatal uptake was the mean of the caudate and putamen uptake. Secondary outcome variables included percentage changes from baseline to month 46 in caudate and putamen [ 123 I] -CIT uptake ratios and percentage changes from baseline to months 22 and 34 for [ 123 I] -CIT up- 219 Not Enrolled in CALM-D-CIT 110 Enrolled rior to Start of CALM-D-CIT 67 Enrolled at Sites Not articipating in CALM-D-CIT 42 Not Interested in Imaging Study 42 Assigned to Receive 40 Assigned to Receive Completed Imaging Studies 40 At Baseline 6 At 10 wk At 22 mo 36 At 34 mo 32 At 46 mo 33 Completed Trial 32 Completed Trial 3 Withdrew From CALM-D but Continued in CALM-D-CIT 2 At 34 mo 1 Lack of Efficacy 1 Other 1 At 46 mo (Lack of Efficacy) 8 Withdrew From CALM-D-CIT 1 At 22 mo (Died) 3 At 34 mo 2 Other Illness 1 Desired to End Study articipation 4 At 46 mo 1 Died 1 Other Illness 2 Desired to End Study articipation 33 Included in Analysis 32 Included in Analysis D indicates arkinson disease; CALM-D, parallel-group, double-blind comparison study of pramipexole and carbidopa/levodopa in the treatment of D; CIT, 2 -carboxymethoxy-3 (4-iodophenyl)tropane American Medical Association. All rights reserved. (Reprinted) JAMA, April 3, 2002 Vol 287, No

4 Table 1. atient Characteristics at Baseline* Characteristic (n = 42) (n = 40) Age, y 61.9 (10.8) 60.1 (11.1) Male, % White, % Time since 1.3 (1.4) 1.6 (1.9) diagnosis, y UDRS scores Initial total 34.6 (13.1) 30.6 (11.4) Initial motor 23.2 (9.7) 21.5 (8.8) -CIT uptake Striatum 3.04 (0.72) 2.91 (0.66) Caudate 4.07 (0.86) 3.90 (0.83) utamen 2.01 (0.68) 1.93 (0.56) Ipsilateral striatum 3.28 (0.75) 3.17 (0.74) Contralateral striatum 2.81 (0.75) 2.65 (0.64) *UDRS indicates Unified arkinson Disease Rating Scale; -CIT, 2 -carboxymethoxy-3 [4-iodophenyl]tropane; contralateral, side opposite to initial symptoms; ipsilateral, side of initial symptoms. Data are mean (SD) unless otherwise noted. take ratio (striatum, putamen, and caudate). Secondary outcomes also included these variables expressed as absolute change in [ 123 I] -CIT uptake ratio from baseline and changes from baseline in UDRS scores (total and motor) after 22, 34, and 46 months. Statistical Analysis Analysis of covariance was used to compare the treatment groups with regard to mean percentage changes (and mean changes) in [ 123 I] -CIT uptake and mean changes in UDRS scores, with the baseline value included as a covariate. Two-tailed t tests were used to compare the adjusted treatment group means. The association between change from baseline in UDRS score (dependent variable) and percentage change from baseline in [ 123 I] -CIT uptake (independent variable) was examined using a multiple regression model that adjusted for initial treatment (pramipexole, levodopa) and baseline UDRS score. This analysis was performed separately for each time point (months 22, 34, and 46). For all analyses, patients were grouped by the intention-to-treat principle according to their original randomized treatment assignment (pramipexole, levodopa) even if they received supplemental levodopa therapy or withdrew from CALM-D, but continued to be followed up in CALM-D-CIT. Two separate analyses were performed, one using only available data and another that incorported imputation of missing follow-up data. Imputation was performed as follows: (1) for patients with complete data at month 22, a regression model was fit with the month 22 value as the dependent variable and the baseline value and treatment group as the independent variables; (2) using this regression model, a missing value at month 22 was imputed given the treatment group and baseline value for a patient with missing data; (3) for patients with complete data at month 34, a regression model was fit with the month 34 value as the dependent variable and the baseline value, month 22 value, and treatment group as the independent variables; and (4) using this regression model, a missing value at month 34 was imputed given the treatment group, baseline value, and month 22 value for a patient with missing data. Steps 3 and 4 were repeated to impute a missing value at month 46 given the treatment group and baseline, month 22, and month 34 values for a patient with missing data. Unless otherwise specified, the analyses reported are those that were performed using only available data. The results obtained using these 2 analysis strategies were similar. All statistical tests were 2-tailed. Statistical analyses were performed using SAS version 8.0 (SAS Institute Inc, Cary, NC) and tested at the.05 level of significance. RESULTS atient Demographics The demographic characteristics of the study cohort at baseline are shown in TABLE 1. The 82 patients participating in the imaging substudy did not differ from the 301 patients in the CALM-D study. 22 The age, sex, and ethnic distributions of patients enrolled in the 2 treatment groups were similar. The patients initially treated with levodopa were slightly less impaired as measured by the baseline UDRS. There was a similar reduction in striatal -CIT uptake consistent with early D in both treatment groups. During the 46-month evaluation period, 9 patients (21.4%) initially treated with pramipexole and 8 patients (20%) initially treated with levodopa withdrew from the study (Figure 1). For patients who did not complete 46 months of follow-up, the mean (SD) baseline striatal -CIT uptake was 2.8 (0.9) in the pramipexole group (n=9) and 3.1 (1.1) in the levodopa group (n=8). For patients who completed 46 months of follow-up, the mean (SD) baseline striatal -CIT uptake was 3.0 (0.7) in the pramipexole group (n=33) vs 2.9 (0.5) in the levodopa group (n=32). One patient in the pramipexole group withdrew because of worsening D with hallucinations; 1 patient in the pramipexole group and 3 patients in the levodopa group withdrew because of worsening medical illness not related to D. There were 4 deaths in the pramipexole group and 2 deaths in the levodopa group that were judged to be unrelated to study drug. Sequential Imaging Analysis Sequential imaging of the entire study cohort showed a mean (SD) decline from baseline in [ 123 I] -CIT striatal uptake of 0.28 (0.31) at 22 months, 0.42 (0.36) at 34 months, and 0.58 (0.40) at 46 months. The corresponding mean (SD) percentage loss from baseline of striatal -CIT uptake was 10.3% (9.8%) at 22 months, 15.3% (12.8%) at 34 months, and 20.7% (14.4%) at 46 months, declining approximately 5.2% per year during the 46-month evaluation period (FIGURE 2). The mean (SD) percentage loss from baseline of [ 123 I] - CIT uptake at 46 months was greater in the putamen (22.5% [19.5%]) than in the caudate (19.6% [13.6%]). Although there was a greater baseline reduction in the side contralateral to initial symptoms (Table 1), the progressive loss of [ 123 I] -CIT uptake in each hemistriatum did not differ JAMA, April 3, 2002 Vol 287, No. 13 (Reprinted) 2002 American Medical Association. All rights reserved.

5 Analysis of the treatment groups demonstrated that the rate of decline in striatal [ 123 I] -CIT uptake from baseline was significantly reduced in the group treated initially with pramipexole compared with the group treated initially with levodopa (FIGURE 3A and TABLE 2). The mean (SD) percentage loss from baseline of [ 123 I] -CIT striatal uptake in the pramipexole vs levodopa groups was 16.0% (13.3%) vs 25.5% (14.1%) at 46 months (=.01). Similarly, comparison of the percentage loss from baseline in the pramipexole group with the levodopa group was 7.1% (9.0%) vs 13.5% (9.6%) at 22 months (=.004) and 10.9% (11.8%) vs 19.6% (12.4%) at 34 months (=.009). utamen and caudate [ 123 I] -CIT uptake showed a similar reduction in the rate of decline in the pramipexole group (Figure 3B and C and Table 2). Analyses that incorporated imputation of missing follow-up data revealed similar results (pramipexole vs levodopa at 46 months): striatal [ 123 I] - CIT uptake, 16.6% (12.7%) vs 24.9% (14.0%) (=.005); caudate [ 123 I] -CIT uptake, 15.6% (11.6%) vs 23.7% (12.5%) (=.003); and putamen [ 123 I] - CIT uptake, 18.6% (18.8%) vs 27.2% (19.3%) (=.05). During the initial 22 months of the study, 19 of patients in the pramipexole group and 22 of patients in the levodopa group were treated with study drug alone without requiring supplemental levodopa. The percentage loss of [ 123 I] -CIT striatal uptake from baseline after 22 months in these Figure 2. rogessive Loss of Striatal -CIT Uptake Baseline 22 Months 34 Months 46 Months β-cit Uptake High -CIT indicates 2 -carboxymethoxy-3 (4-iodophenyl)tropane. Single-photon emission computed tomography (SECT) [ 123 I] -CIT images of progressive striatal dopamine transporter loss during the 46-month evaluation period for a representative patient. Loss of activity is more marked in the putamen than in the caudate. Levels of SECT activity are color-encoded from low (black) to high (yellow/white). Low Figure 3. Change From Baseline in -CIT Uptake A Striatal β-cit Uptake B utamen β-cit Uptake C Caudate β-cit Uptake Mean Change From Baseline, % No. of atients Scan Time, mo Scan Time, mo Scan Time, mo CIT indicates 2 -carboxymethoxy-3 (4-iodophenyl)tropane. The rate of loss of striatal -CIT uptake (specific/nondisplaceable activity) is reduced for those subjects initially treated with pramipexole compared with those initially treated with levodopa. The mean (SE) percentage loss of uptake from baseline is indicated during a 46-month period American Medical Association. All rights reserved. (Reprinted) JAMA, April 3, 2002 Vol 287, No

6 study participants was 6.9% (9.0%) in the pramipexole group compared with 12.0% (11.1%) in the levodopa group (=.08), a relative decrease in the pramipexole group of 43%. Among study participants who did require supplemental levodopa by 22 months after baseline, the percentage loss of [ 123 I] - CIT striatal uptake from baseline after 22 months was 7.3% (9.2%) in the pramipexole group compared with 15.5% (7.0%) in the levodopa group (=.009), and after 46 months from baseline was 17.2% (15.5%) in the pramipexole group vs 28.9% (16.4%) in the levodopa group (=.03). The short-term effect of pramipexole (n=7) and levodopa (n=6) on [ 123 I] -CIT uptake was further assessed in the subset of study participants who underwent imaging 10 weeks after initiating treatment. Comparison of [ 123 I] -CIT striatal uptake at 10 weeks with baseline showed a decrease of 5.4% (12.2%) in the pramipexole group and 4.6% (4.4%) in the levodopa group. Correlation of [ 123 I] -CIT Uptake and UDRS Score The mean total and motor UDRS scores obtained in the defined off state were reduced in the levodopa group at 22 months compared with baseline and the pramipexole group, but were not significantly different from baseline or the pramipexole group by 34 or 46 months (TABLE 3). There was a correlation of the percentage loss of striatal [ 123 I] -CIT uptake from baseline with the change in total UDRS score from baseline in all patients (r= 0.01, =.94 at 22 months; r= 0.30, =.01 at 34 months; and r= 0.40, =.001 at 46 months from baseline). The percentage loss of putamen and caudate [ 123 I] - CIT uptake from baseline showed increasing correlation with the change in UDRS score from baseline as the duration of assessment increased (putamen: r= 0.03, =.78 at 22 months; r= 0., =.001 at 34 months; and r= 0., =.001 at 46 months from baseline; caudate: r=0.02, =.89 at 22 months; r= 0.20, =.11 at 34 months; and r= 0.35, =.005 at 46 months from baseline). COMMENT In vivo dopamine transporter imaging with [ 123 I] -CIT SECT demonstrated reduced loss of striatal [ 123 I] -CIT uptake in patients with D treated initially with pramipexole compared with those treated initially with levodopa during a 46-month evaluation period. As [ 123 I] -CIT SECT is a quantitative biomarker for striatal dopamine neuron terminals, these data indicate that treatment with pramipexole, levodopa, or both may modify the dopaminergic neuronal degeneration of D. The identification of diseasemodifying therapies for D is a major unmet need. Studies that evaluate neuroprotective effects of medications have been limited by the lack of a clear end point defining neuroprotection and confounded by potential simultaneous symptomatic and neuroprotective benefit. 31,32 In vivo imaging offers the potential of an objective method to Table 2. Change in [ 123 I] -CIT Uptake in Sequential Scans After Initial Treatment With or * (n = ) 22 Months 34 Months 46 Months (n = ) (n = 35) (n = 36) (n = 33) (n = 32) % Change From Baseline, Mean (SD) Striatum 7.1 (9.0) 13.5 (9.6) (11.8) 19.6 (12.4) (13.3) 25.5 (14.1).01 utamen 7.9 (13.7) 16.9 (12.9) (15.3) 24.2 (15.5) (19.0) 28.1 (18.7).03 Caudate 6.4 (8.8) 11.8 (9.4) (11.7) 17.2 (12.4) (12.6) 24.1 (13.3).01 Ipsilateral striatum 7.2 (9.4) 14.3 (10.9) (12.8) 19.6 (12.2) (13.6) 25.7 (14.4).01 Contralateral striatum 6.8 (10.1) 12.6 (10.0) (13.0) 19.4 (14.4) (14.4) 25.3 (14.7).02 Change From Baseline, Mean (SD) Striatum 0.19 (0.28) 0.37 (0.31) (0.36) 0.53 (0.33) (0.38) 0.71 (0.38).009 utamen 0.16 (0.27) 0.31 (0.30) (0.31) 0.44 (0.28) (0.37) 0.52 (0.33).03 Caudate 0.23 (0.) 0.44 (0.) (0.49) 0.62 (0.46) (0.49) 0.91 (0.50).01 Ipsilateral striatum 0.22 (0.33) 0.43 (0.37) (0.43) 0.59 (0.38) (0.45) 0.80 (0.47).01 Contralateral striatum 0.17 (0.29) 0.32 (0.29) (0.35) 0.47 (0.33) (0.36) 0.63 (0.32).01 * -CIT indicates 2 -carboxymethoxy-3 [4-iodophenyl]tropane; contralateral, side opposite to initial symptoms; ipsilateral, side of initial symptoms. Table 3. Change in UDRS ( Defined Off ) After Initial Treatment With or * UDRS Score (SD) (n = ) 22 Months 34 Months 46 Months (n = 38) (n = 35) (n = 35) (n = 33) (n = 32) Total 0.9 (12.2) 3.3 (8.1) (10.7) 0.7 (11.5) (9.9) 4.0 (8.7).61 Motor 0.0 (8.2) 2.5 (6.0) (8.0) 0.5 (7.9) (7.4) 2.1 (6.2).84 *UDRS indicates Unified arkinson Disease Rating Scale JAMA, April 3, 2002 Vol 287, No. 13 (Reprinted) 2002 American Medical Association. All rights reserved.

7 monitor neuronal degeneration unaffected by a short-term symptomatic drug effect. 33 Several recent studies have used neuroimaging to investigate the possible neuroprotective effects of dopamine agonists. A preliminary study that assessed the effects of ropinirole hydrochloride did not demonstrate a change in neuronal loss as measured by [ 18 F]DOA positron emission tomography, but showed a trend toward reduction in the change of [ 18 F]DOA uptake in the patients treated with the dopamine agonist. 34 Initial analysis of our data in the CALM-D-CIT study after 22 months showed a similar trend toward reduction in the rate of loss of [ 123 I] -CIT uptake in patients initially treated with pramipexole compared with those treated with levodopa. 22 The 22- month data presented in this study differ from the previous study because these data were analyzed using improved reconstruction analysis technology developed during the study and designed to more accurately measure count density in regions with low counts. During the past 2 years, we have both improved our reconstruction analysis technology and extended the duration of the double-blind, parallelgroup design, while retaining 79% of enrolled patients at 46 months. We now present data demonstrating a significant and persistent reduction in the rate of loss of [ 123 I] -CIT uptake in patients with D initially treated with pramipexole compared with levodopa during the 46-month evaluation period. Evidence from animal studies, healthy humans, and patients with D has demonstrated that [ 123 I] -CIT uptake is a biomarker for striatal dopamine transporter density and also dopamine neuronal terminal integrity. 9,25,35,36 rogressive nigrostriatal dopamine neuron loss is the predominant pathologic finding of D. Therefore, the relative reduction in the rate of loss of [ 123 I] -CIT uptake in those patients treated with pramipexole compared with levodopa most likely reflects a reduction (by pramipexole) or acceleration (by levodopa) in the progressive loss of striatal dopamine neuronal function. Although it remains possible that the difference in the pramipexole vs levodopa groups is because of an interaction between pramipexole, levodopa, or both and the dopamine transporter, it is likely that such an interaction would be present shortly after initiating therapy. In this study, short-term sequential imaging at 10 weeks did not demonstrate any significant effect of either pramipexole or levodopa on [ 123 I] -CIT uptake. These data were also consistent with prior studies showing no short-term effects of levodopa, selegiline, or pergolide on [ 123 I] -CIT uptake. 37,38 Approximately 20% of the study cohort withdrew from CALM-D-CIT before the month 46 visit. However, in both treatment groups, the baseline transporter density measurements in patients who withdrew from the trial were similar to those in patients who completed the trial. The frequency and reasons for withdrawal were also similar in the 2 groups and the treatment effects were reasonably consistent over time, including month 22 in which 95% of the cohort remained. The analyses that incorporated imputation of missing follow-up data yielded results that were similar to those based on only available follow-up data. The regression-based imputation strategy that we used seems reasonable in our setting and more appropriate than an ad-hoc approach such as carrying forward the last available observation. For all of these reasons, we do not believe that participant withdrawal had a major impact on the overall results. Since this study compared 2 active medications without a placebo group, these data cannot directly distinguish whether the difference in the rate of loss of [ 123 I] -CIT uptake in the treatment groups results from a decrease due to pramipexole, an increase due to levodopa, or both. However, indirect evidence from preclinical studies and prior imaging studies suggests that a decrease in the percentage loss of [ 123 I] - CIT uptake due to exposure to pramipexole rather than an increase due to exposure to levodopa is more likely. reclinical data regarding the effects of levodopa suggest both possible toxic and protective action, 4,5 whereas emerging data regarding dopamine agonists have supported a neuroprotective action via antioxidant or antiapoptotic mechanisms. 7,8,40 In prior imaging studies, the annual percentage loss of [ 123 I] -CIT striatal uptake of untreated patients with D was 6.8%, similar to the levodopa group in this study. 41 Furthermore, the percentage loss from baseline of [ 123 I] - CIT striatal uptake after 46-month follow-up in this study in those patients initially treated with pramipexole who did require supplemental levodopa by 22 months remained reduced compared with those patients initially treated with levodopa also requiring supplemental levodopa by 22 months. These imaging data suggest that treatment with pramipexole may have decreased the rate of loss of [ 123 I] -CIT uptake despite treatment with levodopa. However, the duration and dose of exposure to supplemental levodopa and the effect of pretreatment with a dopamine agonist on a possible levodopa disease-modifying effect have not been fully evaluated. Studies are under way to directly assess the effect of treatment with levodopa compared with placebo on the rate of loss of [ 123 I] - CIT uptake in patients with early D that will further elucidate the relative effects of pramipexole and levodopa on [ 123 I] -CIT uptake. 5 A key therapeutic issue is whether the effects of pramipexole and levodopa on the rate of loss of [ 123 I] -CIT uptake are associated with a persistent change in clinical function in patients with D. Several clinical end points for progressive functional decline in D have been used, including UDRS in the defined off state or after drug washout up to 2 weeks, time to need for dopaminergic therapy, or time to the development of motor fluctuations. 5,32,42 These end points reflect the complex clinical progression of D symptoms and disability. The changes in imag American Medical Association. All rights reserved. (Reprinted) JAMA, April 3, 2002 Vol 287, No

8 ing outcome measures such as [ 123 I] - CIT provide a method to assess the striatal dopamine pathologic features of D. In several cross-sectional studies of D cohorts, the reduction in [ 123 I] -CIT correlates with the increasing severity measured by the UDRS. 9,25 However, in prior longitudinal studies, there has been no clear correlation between change in either [ 123 I] - CIT or [ 18 F]DOA uptake and the change in UDRS score. 15,16 Several explanations for this poor correlation have been suggested. First, the UDRS score is likely confounded by the effects of anti-d medications, despite patient evaluation in the defined off state because of long-duration effects of these treatments. 43 Second, in early D the temporal patterns for rate of loss of dopamine transporter and the change in UDRS score may not be congruent. This is best illustrated by data demonstrating a loss of approximately 40% to 50% of striatal [ 123 I] -CIT uptake at the time of diagnosis when clinical symptoms measured by the UDRS may be minimal. These data suggest that in patients with early D clinical and imaging outcomes provide complementary data and that long-term follow-up will be required to correlate changes in clinical and imaging outcomes. In this study, the loss of striatal [ 123 I] -CIT uptake from baseline was significantly correlated with the change in UDRS score from baseline at the 46-month evaluation, suggesting that the correlation between clinical and imaging outcomes will emerge with longer monitoring. We plan to extend the follow-up of this imaging cohort and examine the associations between changes in the loss of striatal [ 123 I] -CIT uptake and the complete clinical data in the CALM-D study. This study demonstrates that [ 123 I] - CIT SECT imaging can detect treatment-related changes in the progressive rate of loss of striatal dopamine transporters in patients with early D. During a 46-month evaluation period, these data show a decrease in the rate of loss of striatal [ 123 I] -CIT uptake in patients initially treated with pramipexole compared with levodopa. These data highlight the need to compare this imaging marker of dopamine neuronal loss with multiple meaningful clinical end points of disease progression in larger, long-term studies to fully assess its clinical relevance. arkinson Study Group Investigators: Steering Committee: Kenneth Marek, MD, John Seibyl, MD, principal investigators for CALM-D-CIT, The Institute for Neurodegenerative Disorders, New Haven, Conn; Ira Shoulson, MD, principal investigator for CALM-D, Robert Holloway, MD, MH, medical director, Karl Kieburtz, MD, MH, Michael McDermott, hd, chief biostatistician, Cornelia Kamp, MBA, CRCC project coordinator, Aileen Shinaman, JD, SG executive director, University of Rochester, Rochester, NY; Stanley Fahn, MD, coprincipal investigator for CALM-D, Columbia University, New York, NY; Anthony Lang, MD, Toronto Western Hospital, University Health Network, Toronto, Ontario; William Weiner, MD, University of Maryland, Baltimore; Mickie Welsh, RN, DNS, ex-officio, University of Southern California, Los Angeles. Author Contributions: Dr Marek, as principal investigator, had full access to all of the data in this study and takes responsibility for the integrity of the data and accuracy of the data analysis. Study concept and design: Marek, Seibyl, Shoulson, Holloway, Kieburtz, McDermott, Kamp, Fahn, Lang, Weiner, Welsh, Mendick, Guerrette, Innis, Wooten, Jankovic, Rodnitzky, Kurlan, LeWitt, Casaceli. Acquisition of data: Marek, Seibyl, Kamp, Shinaman, Welsh, Sayers, Early, Zoghbi, Innis, Russell, Fussell, ahwa, Montgomery, R. feiffer, B. feiffer, Wooten, Rost-Ruffner, Hubble, Weeks, Jankovic, Waters, etzinger, Miyasaki, Duff, Sime, Hammerstad, Stone, Alexander-Brown, Barclay, Sutherland, Dobson, Standaert, Tennis, Kurlan, Gardiner, Berry, Lewitt, DeAngelis, Factor, Brown, Evans, Dillon, Stacy, Brocht, Casaceli, Daigneault, Hodgeman. Analysis and interpretation of data: Marek, Seibyl, Holloway, Kieburtz, McDermott, Fahn, Weiner, Early, Zoghbi, Innis, Jankovic, Kurlan, LeWitt, Brocht, Watts. Drafting of the manuscript: Marek, Weiner, Welsh, Zoghbi, Innis, Montgomery, Jankovic, Duff, Gardiner, Berry. Critical revision of the manuscript for important intellectual content: Marek, Seibyl, Shoulson, Holloway, Kieburtz, McDermott, Kamp, Shinaman, Fahn, Lang, Weiner, Mendick, Guerrette, Sayers, Early, Russell, Fussell, ahwa, R. feiffer, B. feiffer, Wooten, Rost-Ruffner, Hubble, Weeks, Jankovic, Waters, etzinger, Miyasaki, Sime, Hammerstad, Stone, Alexander-Brown, Barclay, Sutherland, Rodnitzky, Dobson, Standaert, Tennis, Kurlan, LeWitt, DeAngelis, Factor, Brown, Evans, Dillon, Stacy, Brocht, Casaceli, Daigneault, Hodgeman, Watts. Statistical expertise: Marek, McDermott, Jankovic, LeWitt. Obtained funding: Marek, Shoulson, Kieburtz, Shinaman. Administrative, technical, or material support: Seibyl, Kieburtz, Kamp, Shinaman, Lang, Mendick, Guerrette, Sayers, Early, Zoghbi, Innis, Fussell, ahwa, Montgomery, Rost-Ruffner, Hubble, Weeks, Jankovic, Miyasaki, Duff, Sime, Sutherland, Rodnitzky, Dobson, Tennis, Kurlan, LeWitt, DeAngelis, Brown, Evans, Dillon, Brocht, Casaceli, Daigneault, Hodgeman, Watts. Study supervision: Marek, Seibyl, Shoulson, Holloway, Kieburtz, Fahn, Wooten, Miyasaki, Barclay. NeuroImaging Center: Susan Mendick, MH, Elizabeth Guerrette, BA, Erica Sayers, Michele Early, The Institute for Neurodegenerative Disorders, New Haven, Conn; Sami Zoghbi, hd, Robert Innis, MD, hd, Yale University, New Haven, Conn. articipating Investigators and Coordinators: David S. Russell, MD, hd, Barbara Fussell, RN, Yale University School of Medicine, New Haven, Conn; Rajesh ahwa, MD, Amy Montgomery, RN, University of Kansas Medical Center, Kansas City; Ronald feiffer, MD, Brenda feiffer, RN, BSN, University of Tennessee Health Care Center, Memphis; Frederick Wooten, MD, Elke Rost-Ruffner, RN, University of Virginia Health Sciences Center, Charlottesville; Jean Hubble, MD, Carolyn Weeks, MT, Ohio State University, Columbus; Joseph Jankovic, MD, Baylor College of Medicine, Houston, Tex; Cheryl Waters, MD, Giselle etzinger, MD, University of Southern California, Los Angeles; Janis Miyasaki, MD, Jan Duff, RN, Elspeth Sime, RN, Toronto Western Hospital, University Health Network, Toronto, Ontario; John Hammerstad, MD, Claudia Stone, RA, Barbara Alexander- Brown, Oregon Health Sciences University, ortland; Lynn Barclay, MD, Laura Sutherland, RN, Ottawa Civic Hospital, Ottawa, Ontario; Robert Rodnitzky, MD, Judith Dobson, RN, University of Iowa Hospitals, Iowa City; David Standaert, MD, hd, Marsha Tennis, RN, Massachusetts General Hospital, Boston; Roger Kurlan, MD, Irenita Gardiner, RN, Debra Berry, MSN, University of Rochester, Rochester, NY; eter LeWitt, MD, Maryan DeAngelis, RN, Clinical Neuroscience Center, Southfield, Mich; Stewart Factor, DO, Diane Brown, RN, Sharon Evans, LN, Albany Medical College, Albany, NY; Sandra Dillon, RN, Columbia University, New York, NY; Mark Stacy, MD, Barrow Neurological Institute, hoenix, Ariz. Biostatistics and Clinical Trials Coordination Center Staff: Alicia Brocht, BS, Cindy Casaceli, MBA, Susan Daigneault, Karen Hodgeman, Arthur Watts, BS, University of Rochester, Rochester, NY. Financial Disclosures: In keeping with the arkinson Study Group conflict of interest guidelines, none of the investigators have any personal financial relationship with the sponsor. All compensation received by investigators for study-related services was paid through contracts between the University of Rochester, Yale University, and the sponsor that was established before the study began. Funding/Support: This study was supported by harmacia Corp, eapack, NJ, and Boehringer Ingelheim harma, Ingelheim, Germany. Role of Sponsor: This study was designed and conducted by the arkinson Study Group and the Institute for Neurodegenerative Disorders. Data were collected, maintained, and analyzed by the arkinson Study Group and the Institute for Neurodegenerative Disorders. The sponsors participated in discussions regarding study design and conduct, reviewed the data, commented on, and provided authorization for the publication. Acknowledgment: We thank the patients and their families who participated in this study. We also thank the Safety Monitoring Committee: W. Jackson Hall, hd, University of Rochester, Rochester, NY; Carl M. Leventhal, MD, Rockville, Md; Stephen Reich, MD, Johns Hopkins, Baltimore, Md; ierre Tariot, MD, chair, University of Rochester, Rochester, NY. Contributions from the following individuals of the harmacia Corp are gratefully acknowledged: Leona Borchert, MD, MH, and Bruno Musch, MD. REFERENCES 1. Bernheimer H, Birkmayer W, Hornykiewicz O, et al. Brain dopamine and the syndromes of arkinson and Huntington, clinical, morpological, and neurochemical correlates. J Neurol Sci. 1973;20: Fearnley J, Lees A. Ageing and arkinson s disease: substantia nigra regional selectivity. Brain. 1991; 114: aulus W, Jellinger K. The neuropathological basis of different clinical subgroups of arkinson s disease. J Neuropathol Exp Neurol. 1991;506: JAMA, April 3, 2002 Vol 287, No. 13 (Reprinted) 2002 American Medical Association. All rights reserved.

9 4. Murer M, Dziewczapolski G, Menalled L, et al. Chronic levodopa is not toxic for remaining dopamine neurons, but instead promotes their recovery, in rats with moderate nigrostriatal lesions. Ann Neurol. 1998;43: Fahn S. arkinson disease, the effect of levodopa, and the ELLDOA trial. Arch Neurol. 1999;56: Iida M, Miyazaki I, Tanaka K, et al. Dopamine D2 receptor-mediated antioxidant and neuroprotective effects of ropinirole, a dopamine agonist. Brain Res. 1999; 838: Olanow C, Jenner, Brooks D. Dopamine agonists and neuroprotection in arkinson s disease. Ann Neurol. 1998;44(suppl 1): Carvey, ieri S, Ling Z. Attenuation of levodopainduced toxicity in mesencephalic cultures by pramipexole. J Neural Transm. 1997;104: Asenbaum S, Brucke T, irker W, et al. Imaging of dopamine transporters with iodine CIT and SECT in arkinson s disease. J Nucl Med. 1997;38: Booij T, Tissingh G, Boer G. [ 123 I]F-SECT shows a pronounced decline of striatal dopamine transporter labelling in early and advanced arkinson s disease. J Neurol Neurosurg sychiatry. 1997;62: Eidelberg D, Moeller J, Ishikawa M, et al. Early differential diagnosis of arkinson s disease with 18Ffluorodeoxyglucose and positron emission tomography. Neurology. 1995;45: Guttman M, Burkholder J, Kish S, et al. [11C]RTI- 32 ET studies of the dopamine transporter in early dopa-naive arkinson s disease. Neurology. 1997;48: Marek K, Seibyl J, Scanley B, et al. [I-123]CIT SECT imaging demonstrates bilateral loss of dopamine transporters in hemi-arkinson s disease. Neurology. 1996;46: Sawle G, layford E, Burn D, Cunnigham V, Brooks D. Separating arkinson s disease from normality: discriminant function analysis of [18F] dopa ET data. Arch Neurol. 1994;51: Marek K, Innis R, Van Dyck C, et al. [ 123 I]beta- CIT SECT imaging assessment of the rate of arkinson s disease progression. Neurology. 2001;57: Morrish, Rakshi J, Bailey D, Sawle G, Brooks D. Measuring the rate of progression and estimating the preclinical period of arkinson s disease with [18F]dopa ET. J Neurol Neurosurg sychiatry. 1998;64: Nurmi E, Ruottinen H, Kaasinen V, et al. rogression in arkinson s disease: a positron emission tomography study with a dopamine transporter ligand [18F]CFT. Ann Neurol. 2000;47: Nurmi E, Ruottinen H, Bergman J, et al. Rate of progression in arkinson s disease: a 6-[18F]fluoro- L-dopa ET study. Mov Disord. 2001;16: irker W, Djamshidian S, Asenbaum S, et al. rogression of dopaminergic degeneration in arkinson s disease and atypical parkinsonism: a longitudinal -CIT SECT study. Mov Disord. 2002;17: McGeer L, Itagaki S, Akiyama H, McGeer EG. Rate of cell death in parkinsonism indicates active neuropathological process. Ann Neurol. 1988;24: arkinson Study Group. Design of a clinical trial comparing pramipexole to levodopa in early D (CALM-D). Clin Neuropharmacol. 2000;23: arkinson Study Group. vs levodopa as initial treatment for arkinson disease: a randomized controlled trial. JAMA. 2000;284: Baldwin RM, Zea-once Y, Zoghbi SS, et al. Evaluation of the monoamine uptake site ligand [ 123 I]methyl 3 -(4-iodophenyl)tropane-2 -carboxylate ([ 123 I] - CIT) in nonhuman primates: pharmacokinetics, biodistribution, and SECT brain imaging coregistered with MRI. Nucl Med Biol. 1993;20: Chang LT. A method for attenuation correction in computed tomography. IEEE Trans Nucl Sci. 1987; 25: Seibyl J, Marek KL, Quinlan D, et al. Decreased single-photon emission computed tomographic [ 123 I]beta-CIT striatal uptake correlates with symptom severity in arkinson s disease. Ann Neurol. 1995; 38: Fahn S, Elton RL, Members of the UDRS Development Committee. Unified arkinson s disease rating scale. In: Recent Developments in arkinson s Disease. Fahn S, et al, eds. Florham ark, NJ: Macmillan Healthcare Information; 1987: Hoehn MM, Yahr MD. arkinsonism: onset, progression and mortality. Neurology. 1967;17: Langston JW, Widner H, Goetz CG, et al. Core Assessment rogram for Intracerebral Transplantations (CAIT). Mov Disord. 1992;7: Laruelle M, Baldwin RM, Malison RT, et al. SECT imaging of dopamine and serotonin transporters with [ 123 I]beta-CIT: pharmacological characterization of brain uptake in nonhuman primates. Synapse. 1993;13: Innis RB, Seibyl J, Scanley BE, et al. Single photon emission computed tomographic imaging demonstrates loss of striatal dopamine transporters in arkinson disease. roc Natl Acad Sci U S A. 1993;90: Shoulson I. Experimental therapeutic of neurodegenerative disorders: unmet needs. Science. 1998; 282: arkinson Study Group. Effects of tocopherol and deprenyl on the progression of disability in early arkinson s disease. N Engl J Med. 1993;328: Marek K, Seibyl J. Imaging: a molecular map for neurodegeneration. Science. 2000;289: Brooks D, Rakski J, avese N, et al. Relative rates of progression of early arkinson s disease patients started on either a dopamine agonist (ropinirole) or levodopa: 2-year and 5-year follow-up 18F-DOA findings. Neurology. 2000;54(suppl 3):A Van Dyck CH, Seibyl J, Malison RT, et al. Agerelated decline in dopamine transporters: analysis of striatal subregions, nonlinear effects, and hemispheric asymmetries. Am J Geriatr sychiatry. 2002; 10: Elsworth J, Al-Tikriti M, Sladek J, et al. Novel radioligands for the dopamine transporter demonstrate the presence of intrastriatal nigral grafts in the MT-treated monkey: correlation with improved behavioral function. Exp Neurol. 1994;126: Ahlskog JE, Uitti RJ, O Connor MK, et al. The effect of dopamine agonist therapy on dopamine transporter imaging in arkinson s disease. Mov Disord. 1999;14: Innis R, Marek K, Sheff K, et al. Treatment with carbidopa/levodopa and selegiline on striatal transporter imaging with [ 123 I] -CIT. Mov Disord. 1999; 14: Little R, Yau L. Intent-to-treat analysis for longitudinal studies with drop-outs. Biometrics. 1996;52: Le W-D, Jankovic J. Are dopamine receptor agonists neuroprotective in arkinson s disease. Drugs Aging. 2001;18: Jennings D, Innis R, Seibyl J, Marek K. [ 123 I] - CIT and SECT assessment of progression in early and late arkinson s disease. Neurology. 2000;56(suppl 3): A Rascol O, Brooks D, Korczyn A, et al. A five-year study of the incidence of dyskinesia in patients with early arkinson s disease who were treated with ropinirole or levodopa. N Engl J Med. 2000;342: Nutt J, Holford N. The response of levodopa in arkinson s disease: imposing pharmacological law and order. Ann Neurol. 1996;: American Medical Association. All rights reserved. (Reprinted) JAMA, April 3, 2002 Vol 287, No